Delhi: Air improves slightly, back in very poor category

Delhi’s air quality witnessed a marginal improvement on Sunday, settling in the very poor category, after having turned severe a day before.

Delhi’s air quality witnessed a marginal improvement on Sunday, settling in the very poor category, after having turned severe a day before.

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Central Pollution Control Board (CPCB) recordings showed that the overall AQI on Sunday was 389, in the very poor zone. This was slightly better than Saturday’s 404, which is considered to be in the severe zone.

Before Saturday, the air quality was in the severe category on November 25, with an AQI reading of 413. On a scale of 0-500, an AQI value between 301 and 400 is considered very poor, while a reading between 401 and 500 is deemed severe.

Kuldeep Srivastava, head of IMD’s regional weather forecasting centre said that the improvement in the air quality was noticed because of a change in the wind direction from easterly to north-westerly on Sunday. The average wind speed had also improved from 5kmph on Saturday to around 8kmph on Sunday.

“On Saturday, Delhi received easterly winds, which carried high moisture content, resulting in pollution particles sticking closer to the surface. The average wind speed was also low, only around 5kmph— which is not enough for dispersal of pollutants,” said Srivastava.

“On Sunday, however, the wind direction changed back to north-westerly and wind speed also improved. The negligible presence of stubble burning smoke from Punjab and Haryana in the city’s PM 2.5 (particulate matter with diameter less than 2.5 micrometres) levels also helped in bringing down pollution levels,” Srivastava explained.

IMD scientists also said that from Monday, wind speed will increase, which will lead to further improvement in the air quality.

Union ministry of earth sciences’ air quality monitoring centre, System of Air Quality and Weather Forecasting and Research (Safar), also said that surface winds are forecasted to increase and air quality is likely to improve marginally by Monday, but it will continue to remain within the very poor category.

“There will be marginal improvement in the air quality owing to slightly better ventilation condition. AQI is likely to further improve on December 8 and December 9 due to better ventilation,” Safar air quality forecast read.